Watercraft having a jet propulsion system that generates improved thrust

ABSTRACT

A watercraft is equipped with a jet propulsion system that has improved output propulsion and energy efficiency. Vanes are disposed within the water passage that extends through the jet propulsion system. The vanes are disposed upstream of an impeller. The vanes substantially correct the rotational motion of the water, which is created by the drive shaft. This assists in minimizing swirl created when the watercraft is turned. This also helps to improve the operational efficiency of the jet propulsion unit.

RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Appln. of Menard, Ser. No. 60/313,026, filed Aug. 20, 2001, the entirety of which is hereby incorporated into the present application by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to jet powered watercraft, especially personal watercraft (“PWC”). More specifically, the invention concerns the jet propulsion system of the watercraft. In particular, the invention is directed to vanes, that are disposed within a water passage at a position upstream of the jet propulsion system.

[0004] 2. Description of Related Art

[0005] Jet powered watercraft have become very popular in recent years for recreational use and for use as transportation in coastal communities. The jet power offers high performance, which improves acceleration, handling and shallow water operation. Accordingly, PWCs, which typically employ jet propulsion, have become common place, especially in resort areas. As use of PWCs has increased, the desire for better performance has become strong.

[0006] Typically, jet powered watercraft, such as PWC's, have a jet propulsion system mounted within the hull that takes in water and expels the water at a high speed to generate thrust to propel the watercraft. To control the direction of the watercraft, a nozzle is generally provided at the outlet of the jet pump to direct the thrust in a desired direction. Thus, in the conventional PWC, turning is achieved by redirecting the thrust.

[0007] In the typical arrangement for a jet propulsion unit, an engine output shaft extends from the engine and is rotationally coupled to a drive shaft. The drive shaft extends into a water passage, which is defined by the hull of the watercraft partially below the water line. The water passage extends from a point forward of the rear of the watercraft to the rear of the watercraft. An impeller is attached to the drive shaft and is disposed within a pump housing portion of the water passage. The drive shaft is sometimes referred to as an impeller shaft.

[0008] During operation, as the drive shaft rotates, the impeller draws water through an inlet disposed at the forward end of the water passage under the hull and discharges the water, at great speed and pressure, through a venturi at the rear end (or outlet) of the water passage. The steering nozzle can be provided at the outlet and can be part of the venturi or a separate element.

[0009] When the watercraft is turned, the rotational momentum of the water in the water passage can negate some of the momentum imparted to the water being circulated at the impeller. Furthermore, the drive shaft in the conventional jet propulsion unit rotates at very high speeds. Accordingly, the rotational motion of the impeller imparts rotational motion to the water being pumped through the water passage. This can result in a slight (but noticeable) drop in output propulsion power for the watercraft. Moreover, any rotational energy imparted by the impeller and drive shaft to the water being pumped through the propulsion unit is energy “lost” by the propulsion unit since the energy cannot be used to generate thrust to propel the watercraft.

[0010]FIG. 7 shows a prior art jet propulsion system 600 disposed within the hull 612 of a watercraft, of which only a portion is shown in broken lines. As shown, an inlet grate 642 is disposed at an inlet 686 to an intake ramp 688 to the jet propulsion system 600. The inlet grate 642 prevents large rocks, weeds, and other debris from entering the water intake ramp 688 and passing through the jet propulsion system 600. A pump support 650 or ride shoe forms the bottom portion 692 of the water intake ramp 688. The pump support 650 is coupled to the hull 612 within the tunnel 694 through fasteners and/or adhesives (not shown). The pump support 650 includes a main body portion 651 having a vertical attachment surface 652, a forward attachment location 654 that is secured to the ride plate 696, and a ramp portion 656. A passage (not shown) extends through the main body portion 651 of the pump support 650. The ramp portion 656 forms the bottom portion 692 of the water intake ramp 688.

[0011] From the water intake ramp 688, water enters into the jet pump 660. The jet pump 660 includes an impeller 670 and a stator 680. The impeller includes blades 672 that extend from a center portion or hub 674 that is coupled to an engine by one or more shafts 698, such as a drive shaft and/or an impeller shaft. The rotation of the impeller 670 pressurizes the water, which then moves over the stator 680 that is made of a plurality of fixed stator blades 682. The role of the stator blades 682 is to decrease the rotational motion of the water so that almost all the energy given to the water is used for thrust, as opposed to swirling the water. As shown, the impeller and the stator 680 are both disposed within a jet propulsion unit housing 690 or pump housing. However, it is also known to position the stator 680 at a position outside of the housing 690 at a position downstream of the housing 690. The housing 690 includes a peripheral wall 691 which defines a passage through which water passes. A forward end 692 of the housing peripheral wall 691 is attached to the vertical attachment surface 654 or the pump support 650. The forward end 692 of the housing peripheral wall 692 defines the inlet into the housing 690.

[0012] Once the water leaves the jet pump 660, it goes through a venturi 610. In this prior art jet propulsion unit 600, the venturi 610 is disposed at the rearward end of the housing 690. Since the venturi's exit diameter is smaller than its entrance diameter, the water is accelerated further, thereby providing more thrust. As shown, the venturi 610 is integrated into the housing 690 and comprises the outlet from the housing 690. A steering nozzle 602 is pivotally attached to the venturi 610 so as to pivot about a vertical axis 694.

[0013] In view of the foregoing, a need has developed for a watercraft with a jet propulsion system that provides improved output propulsion power for the watercraft and improved energy efficiency. In other words, a need has developed for a watercraft design where the effect of the swirl in the inlet created when the watercraft turns is minimized.

SUMMARY OF THE INVENTION

[0014] Therefore, one aspect of embodiments of this invention provides a watercraft having a jet propulsion system that operates with improved output propulsion power and improved energy efficiency.

[0015] Another aspect of the present invention provides a plurality of vanes which reduce rotational movement of water passing through the jet propulsion system.

[0016] An additional aspect of the present invention provides the plurality of vanes at a location upstream of an impeller of the jet propulsion system.

[0017] In summary, this invention is directed to a watercraft having a hull, a water passage extending from a position forward of a rear of the hull to the rear or the hull, an engine mounted within the hull, and a jet propulsion unit comprising a portion of the water passage. The jet propulsion unit comprises a pump housing, a drive shaft with a first end and a second end, the first end being operatively connected to the engine, and an impeller operatively attached to the drive shaft second end. The impeller is disposed within the pump housing. A plurality of vanes extend into the water passage upstream of the impeller.

[0018] This invention is also directed to a jet propulsion unit pump support comprising a generally ring shaped body comprising an inner peripheral wall defining a passage extending therethrough, a plurality of vanes being disposed on the inner peripheral wall, and a pump housing attachment surface, which is configured for attachment to a pump housing.

[0019] This invention is also directed to a jet propulsion unit vane insert comprising a generally ring shaped body having an inner peripheral wall defining a passage extending therethrough, and a plurality of vanes disposed on the inner peripheral wall.

[0020] Preferably, the watercraft is a personal watercraft (PWC). The PWC can be a straddle type seated PWC or a stand-up PWC. Additionally, the watercraft could be different types of jet powered watercraft, such as a jet boat, or a sport boat.

[0021] These and other aspects of this invention will become apparent upon reading the following disclosure in accordance with the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] An understanding of the various embodiments of the invention may be gained by virtue of the following figures, of which like elements in various figures will have common reference numbers, and wherein:

[0023]FIG. 1 illustrates a side view of a watercraft in accordance with the preferred embodiment of the invention;

[0024]FIG. 2 is a top view of the watercraft of FIG. 1;

[0025]FIG. 3 is a front view of the watercraft of FIG. 1;

[0026]FIG. 4 is a back view of the watercraft of FIG. 1;

[0027]FIG. 5 is a bottom view of the hull of the watercraft of FIG. 1;

[0028]FIG. 6 illustrates an alternative stand-up type watercraft;

[0029]FIG. 7 illustrates an enlarged partial side view in cross section of the stern of the watercraft showing a prior art jet propulsion system;

[0030]FIG. 8 illustrates an enlarged partial side view in cross section of the stern of the watercraft showing a first embodiment of the jet propulsion system of the present invention;

[0031]FIG. 9 is an enlarged side view in cross-section of a pump support shown in FIG. 8;

[0032]FIG. 10 is a front view of the pump support shown in FIG. 9,

[0033]FIG. 11 is a perspective view of the pump support of FIG. 9;

[0034]FIG. 12 illustrates an alternative embodiment of a pump support utilized in the jet propulsion system of the present invention;

[0035]FIG. 13 illustrates partial side view in cross section of the stern of the watercraft showing another embodiment of the jet propulsion system of the present invention;

[0036]FIG. 14 is an enlarged side view in cross-section of a vane insert shown in FIG. 13; and

[0037]FIG. 15 illustrates partial side view in cross section of the stern of the watercraft showing another embodiment of the jet propulsion system of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0038] The invention is described with reference to a PWC for purposes of illustration only. However, it is to be understood that the jet propulsion systems described herein can be utilized in any watercraft such as a sport boat. Further, the jet propulsion system of this invention has broad application and is not intended to be limited to watercraft.

[0039] The general construction of a personal watercraft 10 in accordance with a preferred embodiment of this invention is shown in FIGS. 1-5. The following description relates to one way of manufacturing a personal watercraft according to a preferred design. Obviously, those of ordinary skill in the watercraft art will recognize that there are other known ways of manufacturing and designing watercraft and that this invention would encompass other known ways and designs.

[0040] The watercraft 10 of FIG. 1 is made of two main parts, including a hull 12 and a deck 14. The hull 12 buoyantly supports the watercraft 10 in the water. The deck 14 is designed to accommodate a rider and, in some watercraft, one or more passengers. The hull 12 and deck 14 are joined together at a seam 16 that joins the parts in a sealing relationship. Preferably, the seam 16 comprises a bond line formed by an adhesive. Of course, other known joining methods could be used to sealingly engage the parts together, including but not limited to thermal fusion, molding or fasteners such as rivets or screws. A bumper 18 generally covers the seam 16, which helps to prevent damage to the outer surface of the watercraft 10 when the watercraft 10 is docked, for example. The bumper 18 can extend around the bow, as shown, or around any portion or all of the seam 16.

[0041] The space between the hull 12 and the deck 14 forms a volume commonly referred to as the engine compartment 20 (shown in phantom). Shown schematically in FIG. 1, the engine compartment 20 accommodates an engine 22, as well as a muffler, tuning pipe, gas tank, electrical system (battery, electronic control unit, etc.), air box, storage bins 24, 26, and other elements required or desirable in the watercraft 10.

[0042] As seen in FIGS. 1 and 2, the deck 14 has a centrally positioned straddle-type seat 28 positioned on top of a pedestal 30 to accommodate a rider in a straddling position. The seat 28 may be sized to accommodate a single rider or sized for multiple riders. For example, as seen in FIG. 2, the seat 28 includes a first, front seat portion 32 and a rear, raised seat portion 34 that accommodates a passenger. The seat 28 is preferably made as a cushioned or padded unit or interfitting units. The first and second seat portions 32, 34 are preferably removably attached to the pedestal 30 by a hook and tongue assembly (not shown) at the front of each seat and by a latch assembly (not shown) at the rear of each seat, or by any other known attachment mechanism. Preferably, the seat portions 32, 34 can be individually tilted or removed completely. One of the seat portions 32, 34 covers an engine access opening (in this case above engine 22) defined by a top portion of the pedestal 30 to provide access to the engine 22 (FIG. 1). The other seat portion (in this case portion 34) can cover a removable storage box 26 (FIG. 1). A “glove compartment” or small storage box 36 may also be provided in front of the seat 28.

[0043] As seen in FIG. 4, a grab handle 38 may be provided between the pedestal 30 and the rear of the seat 28 to provide a handle onto which a passenger may hold. This arrangement is particularly convenient for a passenger seated facing backwards for spotting a water skier, for example. Beneath the handle 38, a tow hook 40 is mounted on the pedestal 30. The tow hook 40 can be used for towing a skier or floatation device, such as an inflatable water toy.

[0044] As best seen in FIGS. 2 and 4 the watercraft 10 has a pair of generally upwardly extending walls located on either side of the watercraft 10 known as gunwales or gunnels 42. The gunnels 42 help to prevent the entry of water in the footrests 46 of the watercraft 10, provide lateral support for the rider's feet, and also provide buoyancy when turning the watercraft 10, since personal watercraft roll slightly when turning. Towards the rear of the watercraft 10, the gunnels 42 extend inwardly to act as heel rests 44. Heel rests 44 allow a passenger riding the watercraft 10 facing towards the rear, to spot a water-skier for example, to place his or her heels on the heel rests 44, thereby providing a more stable riding position. Heel rests 44 could also be formed separate from the gunnels 42.

[0045] Located on both sides of the watercraft 10, between the pedestal 30 and the gunnels 42 are the footrests 46, which are designed to accommodate a rider's feet in various riding positions. To this effect, the footrests 46 each have a forward portion 48 angled such that the front portion of the forward portion 48 (toward the bow of the watercraft 10) is higher, relative to a horizontal reference point, than the rear portion of the forward portion 48. The remaining portions of the footrests 46 are generally horizontal. Of course, any contour conducive to a comfortable rest for the rider could be used. The footrests 46 may be covered by carpeting 50 made of a rubber-type material, for example, to provide additional comfort and traction for the feet of the rider.

[0046] A reboarding platform 52 is provided at the rear of the watercraft 10 on the deck 14 to allow the rider or a passenger to easily reboard the watercraft 10 from the water. Carpeting or some other suitable covering may cover the reboarding platform 52. A retractable ladder (not shown) may be affixed to the transom 54 to facilitate boarding the watercraft 10 from the water onto the reboarding platform 52.

[0047] Referring to the bow 56 of the watercraft 10, as seen in FIGS. 2 and 3, watercraft 10 is provided with a hood 58 located forwardly of the seat 28 and a helm assembly 60. A hinge (not shown) is attached between a forward portion of the hood 58 and the deck 14 to allow hood 58 to move to an open position to provide access to the front storage bin 24 (FIG. 1). A latch (not shown) located at a rearward portion of hood 58 locks hood 58 into a closed position. When in the closed position, hood 58 prevents water from entering front storage bin 24. Rearview mirrors 62 are positioned on either side of hood 58 to allow the rider to see behind. A hook 64 is located at the bow 56 of the watercraft 10. The hook 64 is used to attach the watercraft 10 to a dock when the watercraft is not in use or to attach to a winch when loading the watercraft on a trailer, for instance.

[0048] As best seen in FIGS. 3, 4, and 5, the hull 12 is provided with a combination of strakes 66 and chines 68. A strake 66 is a protruding portion of the hull 12. A chine 68 is the vertex formed where two surfaces of the hull 12 meet. The combination of strakes 66 and chines 68 provide the watercraft 10 with its riding and handling characteristics. Sponsons 70 are located on both sides of the hull 12 near the transom 54. The sponsons 70 preferably have an arcuate undersurface that gives the watercraft 10 both lift while in motion and improved turning characteristics. The sponsons are preferably fixed to the surface of the hull 12 and can be attached to the hull by fasteners or molded therewith. Sometimes it may be desirable to adjust the position of the sponson 70 with respect to the hull 12 to change the handling characteristics of the watercraft 10 and accommodate different riding conditions.

[0049] As best seen in FIGS. 3 and 4, the helm assembly 60 is positioned forwardly of the seat 28. The helm assembly 60 has a central helm portion 72, that may be padded, and a pair of steering handles 74, also referred to as a handle bar. One of the steering handles 74 is preferably provided with a throttle lever 76, which allows the rider to control the speed of the watercraft 10. As seen in FIG. 2, a display area or cluster 78 is located forwardly of the helm assembly 60. The display cluster 78 can be of any conventional display type, including LCD (liquid crystal displays), dials or LED (light emitting diodes). The central helm portion 72 may also have various buttons 80, which could alternatively be in the form of levers or switches, that allow the rider to modify the display data or mode (speed, engine rpm, time . . . ) on the display cluster 78 or to change a condition of the watercraft 10 such as trim (the pitch of the watercraft).

[0050] The helm assembly 60 may also be provided with a key receiving post 82, preferably located near a center of the central helm portion 72. The key receiving post 82 is adapted to receive a key (not shown) that starts the watercraft 10. As is known, the key is typically attached to a safety lanyard (not shown). It should be noted that the key receiving post 82 may be placed in any suitable location on the watercraft 10.

[0051] Returning to FIGS. 1 and 5, the watercraft 10 is generally propelled by a jet propulsion system 84, which includes a jet propulsion unit or jet pump. The jet propulsion system 84 is shown schematically in FIG. 1. As known, the jet propulsion system 84 pressurizes water to create thrust. The water is first scooped from under the hull 12 through an inlet 86, which preferably has a grate (not shown in detail in FIGS. 1 and 5). Water flows from the inlet 86 through a water intake ramp 88. The top portion 90 of the water intake ramp 88 is formed by the hull 12, and a ride shoe (not shown in detail in FIGS. 1 and 5) forms its bottom portion 92. Alternatively, the intake ramp 88 may be a single piece or an insert to which the jet propulsion system 84 attaches. In such cases, the intake ramp 88 and the jet propulsion system 84 are attached as a unit in a recess in the bottom of hull 12.

[0052] From the intake ramp 88, water enters the jet propulsion system 84. The jet propulsion system 84 is located in a formation in the hull 12, referred to as the tunnel 94. The tunnel 94 is defined at the front, sides, and top by the hull 12 and is open at the transom 54. The bottom of the tunnel 94 is closed by the ride plate 96. The ride plate 96 creates a surface on which the watercraft 10 rides or planes at high speeds.

[0053] The jet propulsion system 84 includes a jet propulsion unit or jet pump (shown schematically in FIG. 1) made of two main parts: the impeller 170 and the stator 180 (as seen in FIG. 8 and detailed below). It is also possible to use a jet pump that has contra-rotating impellers rather than an impeller and a stator.

[0054] The impeller 170 is coupled to the engine 22 by one or more shafts 98, such as a drive shaft and/or an impeller shaft. Alternatively, the one or more shafts 98 could be operatively connected to one another through a gearbox or clutch.

[0055] In operation, the rotation of the impeller 170 pressurizes the water, which then moves over the stator 180 that is made of a plurality of fixed stator blades 182. The role of the stator blades 182 is to decrease the rotational motion of the water so that almost all the energy given to the water is used for thrust, as opposed to swirling the water. Once the water leaves the jet propulsion system 84, it goes through a venturi 100. Since the venturi's exit diameter is smaller than its entrance diameter, the water is accelerated further, thereby providing more thrust. A steering nozzle 102 is pivotally attached to the venturi 100 so as to pivot about a vertical axis 104. The steering nozzle 102 could also be supported at the exit of the tunnel 94 in other ways without a direct connection to the venturi 100 or could be formed as the venturi 100. Alternatively, the nozzle 102 may be replaced by a rudder that re-directs the pressurized water for steering.

[0056] The steering nozzle 102 is operatively connected to the helm assembly 60 preferably via a push-pull cable (not shown) such that when the helm assembly 60 is turned, the steering nozzle 102 pivots. This movement redirects the water coming from the venturi 100, so as to steer the watercraft 10 in the desired direction. Optionally, the steering nozzle 102 may be gimbaled to allow it to move around a second horizontal pivot axis (not shown). The up and down movement of the steering nozzle 102 provided by this additional pivot axis is known as trim and controls the pitch of the watercraft 10.

[0057] When the watercraft 10 is moving, its speed is measured by a speed sensor 106 attached to the transom 54 of the watercraft 10. The speed sensor 106 has a paddle wheel 108 that is turned by the flow of water. In operation, as the watercraft 10 goes faster, the paddle wheel 108 turns faster in correspondence. An electronic control unit (not shown) connected to the speed sensor 106 converts the rotational speed of the paddle wheel 108 to the speed of the watercraft 10 in kilometers or miles per hour, depending on the rider's preference. The speed sensor 106 may also be placed in the ride plate 96 or at any other suitable position. Other types of speed sensors, such as pitot tubes, and processing units could be used, as would be readily recognized by one of ordinary skill in the art.

[0058] The watercraft 10 may be provided with the ability to move in a reverse direction. With this option, a reverse gate 110, seen in FIG. 4, is used. The reverse gate 110 is pivotally attached to the sidewalls of the tunnel 94 or directly on the venturi 100 or the steering nozzle 102. To make the watercraft 102 move in a reverse direction, the rider pulls on a reverse handle 112 (FIG. 1) operatively connected to the reverse gate 110. The reverse gate 110 then pivots in front of the outlet of the steering nozzle 102 and redirects the water leaving the jet propulsion system 84 towards the front of the watercraft, thereby thrusting the watercraft 10 rearwardly. The reverse handle 112 can be located in any convenient position near the operator, for example adjacent the seat 28 as shown or on the helm 60.

[0059] Alternatively, this invention can be embodied in a stand-up type personal watercraft 120, as seen in FIG. 6. Stand-up watercraft 120 are often used in racing competitions and are known for high performance characteristics. Typically, such stand-up watercraft 120 have a lower center of gravity and a more concave hull 122. The deck 124 may also have a lower profile. In this watercraft 120, the seat is replaced with a standing platform 126. The operator stands on the platform 126 between the gunnels 128 to operate the watercraft. The steering assembly 130 is configured as a pivoting handle pole 132 that tilts up from a pivot point 134 during operation, as shown in FIG. 6. At rest, the handle pole 132 folds downwardly against the deck 124 toward the standing platform 126. Otherwise, the components and operation of the watercraft 120 are similar to watercraft 10.

[0060]FIG. 8 shows a first preferred embodiment of the jet propulsion system 84 of the present invention. As shown, the jet propulsion system 84 is disposed within the hull 12, of which only a portion is shown in broken lines to reveal the details of the jet propulsion system 84. A pump support 140 or ride shoe forms the bottom portion 92 of the water intake ramp 88. The pump support 140 is coupled to the hull 12 within the tunnel 94 through fasteners and/or adhesives (not shown). The pump support 140 includes a main body portion 142 having a vertical attachment surface 144, a forward attachment location 148, which is secured to the ride plate 96, and a ramp portion 150. A passage 146 extends through the pump support main body portion 142. The ramp portion 150 extends forwardly into the water intake ramp 88 from the main body portion 142. The ramp portion 150 is also disposed between the forward attachment location 148 and the vertical attachment surface 144. The ramp portion 150 forms the bottom portion 92 of the water intake ramp 88. An outer wall 152 extends from the main body portion 142 of the pump support 140 and is secured to the tunnel 94.

[0061] From the water intake ramp 88, water enters into the jet pump 160 through the inlet 86, preferably through a grate 87. The jet pump 160 includes an impeller 170 and a stator 180, both of which are preferably disposed within a housing 190. The impeller includes blades 172 that extend from a center portion or hub 174 that is coupled to the engine 22 by one or more shafts 98, such as a drive shaft and/or an impeller shaft, as would be known to one skilled in the art. The shaft 98 can be called either a drive shaft or impeller shaft and functions to transmit the driving force of the engine 22 to the impeller 170. In the preferred embodiment, the shaft 98 bisects the watercraft into port and starboard sides. As is also shown, the shaft 98 is preferably disposed horizontally within the hull 12. Those skilled in the art would readily appreciate, however, that the shaft 98 could be angled with respect to the horizontal. While a single shaft 98 is shown, those skilled in the art would appreciate that the shaft 98 could comprise two or more shafts connected together. Alternatively, the shaft 98 could be operatively connected to the engine 22 through transmission elements such as a gear box or clutch.

[0062] The rotation of the impeller 170 pressurizes the water, which then moves over the stator 180 that is made of a plurality of fixed stator blades 182. The stator blades 182 decrease the rotational motion of the water so that almost all the energy given to the water is used for thrust, as opposed to swirling the water. Again, the impeller and the stator 180 are both disposed within a housing 190. However, it is also known to position the stator 180 at a position outside of the housing 190 at a position downstream of the housing 190. The housing 190 includes a peripheral wall 191 defining a conduit. The forward end 192 of the housing peripheral wall 191 defines the inlet into the housing 190. The forward end 192 of the housing peripheral wall 191 is coupled to the vertical attachment surface 144 of the pump support main body portion 142 through the use of mechanical fasteners or adhesives (not shown). The impeller 170, stator 180, and housing 190 may be of any suitable design known in the art.

[0063] A water passage 95, through which water passes from left to right, or upstream to downstream, as illustrated in FIG. 8, is defined by the inlet 86, the water intake ramp 88, the pump support passage 146, the jet pump 160, the venturi 100 and the steering nozzle 102. The inlet 86 is disposed at the upstream portion of the water intake ramp 88. The pump support 140 is disposed at the downstream portion of the water intake ramp 88.

[0064] As is further shown in FIG. 8, a plurality of vanes 200 are disposed in the water passage 95 at a position upstream of the impeller 170. Specifically, the vanes 200 are disposed on the pump support 140 and extend into the pump support passage 146. The vanes 200 are preferably fixed to the pump support 140, and thus are substantially fixed to the hull 12, since the pump support 140 is fixed within the tunnel 94 of the hull 12. Accordingly, in this embodiment of the invention, the vanes 200 are also substantially fixed within the water intake ramp 88. In this embodiment of the invention, the vanes 200 are disposed proximate to the jet propulsion system inlet, which is defined by the forward end 192 of the jet propulsion system housing peripheral wall 191.

[0065] In greater detail, FIG. 9 is an enlarged view showing the pump support 140 from the side in a cross-sectional view. As is shown in this view, the vanes 200 have a leading edge 202 and a trailing edge 204, which is downstream of the leading edge 202. The leading edge 202 is angled rearwardly (toward the housing 190), such that the leading edge 202 is disposed at an acute angle relative to a plane perpendicular to a longitudinal axis of the shaft 98 (shown in phantom). Angling the leading edge 202 of the vanes 200 helps to minimize clogging of the water passage 95, because weeds and foreign objects are less likely to become entrapped on the vanes 200. While it is preferred that the leading edges 202 of the vanes 200 be rearwardly-sloping, the present invention also encompasses vanes that are forwardly-sloping (sloped away from the pump housing 190) or not sloping at all (i.e., the leading edge 202 is perpendicular to the shaft 98). Likewise, the trailing edges 204 of the vanes 200 are shown disposed substantially perpendicularly to the shaft 98. However, the trailing edges 204 alternatively may also be sloped forwardly or rearwardly. In this embodiment of the invention the vanes 200 are straight, and thus, the leading edge 202, the trailing edge 204 and the longitudinal axis of the drive shaft 98 are disposed in the same plane. Additionally, the vanes 200 are disposed such that a plane perpendicular to the shaft 98 intersects each vane 200.

[0066]FIG. 10 shows the pump support 140 in a front elevation view. In this illustration, it can be seen that the vanes 200 substantially surround the shaft 98. Additionally, the shaft 98 preferably has a generally circular cross-section, and the vanes 200 are concentrically disposed about the shaft 98. Each of the vanes 200 preferably has the same predetermined length, and, therefor is separated from the shaft 98 by a substantially equal predetermined distance. However, as would be appreciated by one skilled in the art, the vanes 200 could also be of unequal lengths and do not necessarily need to be disposed concentrically with respect to the shaft 98. Additionally, one skilled in the art would recognize that the precise design and dimensions of the vanes 200 depends on the particular design of the watercraft in which they are used.

[0067] Additionally, the length of the vanes 200 should be long enough to impede the generation of rotational motion to the water in the water passage 95 but also small enough to permit large foreign objects, such as weeds, to pass therethrough. Those skilled in the art would readily appreciate that, if the vanes 200 extended almost to the surface of the shaft 98, there would be a tendency for the vanes 200 to act as a grate, potentially entrapping solid debris sucked into the water passage 95 by the impeller 170. Therefore, in the preferred embodiment of the present invention, vanes 200 do not extend nearly to the surface of the shaft 98. Instead, the vanes 200 extend a predetermined distance into the water passage 95 toward the shaft 98. It is contemplated, however, that the vanes 200 could extend almost entirely to the surface of the shaft 98 without deviating from the scope of the present invention.

[0068]FIG. 10 also shows that the main body portion 142 of the pump support 140 has a generally ring shape. As was shown previously in FIG. 8, the outer wall 152 of the pump support 140 is secured within the tunnel 94. The pump support 140 further includes an inner surface 260 which is preferably annular in shape and concentrically disposed about the shaft 98. Preferably, at least six vanes 200 are disposed in the water passage 95. As is shown in FIG. 10, eight vanes 200 are disposed on the pump support 140. The eight vanes 258 are shown being evenly spaced around the inner peripheral surface 260. As would be appreciated by those skilled in the art, any number of vanes can be used, and the vanes need not be evenly spaced.

[0069]FIG. 11 shows the pump support 140 in a perspective view. As shown, the pump support 140 is preferably a single unit molded from plastic, or composite material, or cast from corrosion resistant metal. However, as would be appreciated from those skilled in the art, the pump support 140 could also be an assembly of individually manufactured elements.

[0070]FIG. 12 shows an alternative configuration of a pump support 300 where each of the vanes 310 are curved. The curvature of the vanes 310 is preferably chosen so that a significant portion of the rotational motion of the water is corrected by the vanes 310. In this embodiment, the vanes are shown having a clockwise curvature, which would preferably be used with a shaft 98 moving in a clockwise motion.

[0071]FIGS. 13 and 14 show another preferred embodiment of the jet propulsion system 400 of the present invention. As shown, the jet propulsion system 400 is disposed within the hull 12, of which only a portion is shown in broken lines to reveal the details of the jet propulsion system 400. In this embodiment, a vane insert 410 is provided in the water passage upstream of the impeller 170. The vane insert 410 has a plurality of vanes 420 that extend inwardly to the water passage 95. Specifically, the vanes 420 are disposed on a ring-shaped vane insert 410 and extend into a passage 411 which extends through the vane insert 410. The vanes 420 are preferably fixed to the vane insert 410. As is shown in this figure, the vane insert 410 is preferably fixed to a pump support 141 through the use of friction, welds (not shown), adhesives (not shown) or mechanical fasteners (also not shown). Thus, the vanes 420 are substantially fixed to the hull 12, since the pump support 141 is fixed within the tunnel 94 of the hull 12. The vanes 420 are also substantially fixed within the water intake ramp 88, as the pump support 141 comprises the downstream portion of the water intake ramp 88. The vanes 420 are preferably disposed proximate to the jet propulsion unit inlet, which is defined by the forward end 192 of the jet propulsion unit housing peripheral wall 191. However, as would be appreciated by one skilled in the art, the vane insert 410 could be disposed at a greater distance away from the jet pump 160. It is also contemplated that the vane insert 410 can also be disposed within the water intake ramp 88 at a position upstream of the pump support 141.

[0072] In greater detail, FIG. 14 is an enlarged view showing the vane insert 410 from the side in a cross-sectional view. The vane insert 410 includes a peripheral wall 412 having an outer surface 413 and an inner surface 414, which is preferably annular in shape and disposed concentrically with respect to the shaft 98. The peripheral wall 412 has a leading edge 418 and a trailing edge 416. The vanes 420 preferably have a configuration substantially similar to the vanes 200 shown in the previous embodiment of the invention shown in FIGS. 8-11. Alternatively, the vanes 420 can have other possible shapes, including but not limited to a curved shape as was previously shown in FIG. 12. As was previously described with respect to the previous embodiments, the vanes 420 can be disposed in a variety of arrangements within the water passage 95. Preferably, eight vanes 420 of equal length are evenly spaced around the inner peripheral surface 411 of the vane insert 410.

[0073] As shown, the vane insert 410 is preferably a single unit molded from plastic, or composite material, or cast from corrosion resistant metal. However, as would be appreciated from those skilled in the art, the vane insert 410 could also be an assembly of individually manufactured elements.

[0074]FIG. 15 shows another preferred embodiment of the jet propulsion system 500 of the present invention. As shown, the jet propulsion system 500 is disposed within the hull 12, of which only a portion is shown in broken lines to reveal the details of the jet propulsion system 500. In this embodiment, a vane insert 410 with a plurality of vanes 420 is disposed within the water passage 95 at a position upstream of the impeller 170. However, unlike the previous embodiments of the invention where the vane insert 410 is disposed within the water intake ramp 88, in this embodiment the vane insert 410 is disposed downstream of the water intake ramp 88 within the jet pump 560. Specifically, the vanes 420 are disposed on the vane insert 410, which is preferably fixed to the jet propulsion unit housing peripheral wall 591 through the use of friction, adhesives (not shown) or mechanical fasteners (also not shown). The vane insert 410 is preferably fixed to a housing peripheral wall 591 of the jet propulsion unit 560 at a position proximate to a peripheral wall forward edge 592, which defines the inlet into the jet propulsion unit 560. Accordingly, the vanes 420 are substantially fixed to the hull 12, since the jet propulsion unit 560 is fixed to the pump support 141, which is fixed within the tunnel 94 of the hull 12. The vanes 420 are preferably disposed proximate to the jet propulsion unit inlet, which is defined by the forward edge 592 of the jet propulsion unit housing peripheral wall 591. Specifically the vanes 420 are preferably disposed between the jet propulsion unit inlet at forward edge 592 and the impeller 170.

[0075] In each of the preferred embodiments, the vanes are sized large enough to significantly reduce the rotational motion of the water before it is propelled by the jet propulsion unit impeller 170. Additionally, in each of the embodiments of the invention previously described, the vanes have been disposed close to the impeller so that the maximum benefit of the vanes is provided and a minimum of rotational motion of the water exists when the water reaches the impeller 170. Further, this positioning of the vanes assists in minimizing swirl at the inlet. However, one skilled in the art would readily understand that the vanes could also be disposed in the water passage at a further distance from the impeller 170.

[0076] As noted above, the jet pump could be made of contra-rotating impellers. In that case, the vanes would be disposed in the same manner. The difference would be that an impeller would replace the stator described above.

[0077] The embodiments described herein are not mutually exclusive and can be used in combination. For example, it is contemplated that the pump support 140 shown in FIG. 8 could be used with the jet propulsion unit 560 of FIG. 15.

[0078] Although the above description contains specific examples of the present invention, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.

[0079] Additionally, as noted previously, this invention is not limited to PWC. For example, the vane assisted steering systems disclosed herein may also be useful in small boats or other floatation devices other than those defined as personal watercrafts. 

What is claimed is:
 1. A watercraft comprising: a hull having a tunnel formed therein that forms a water passage with an inlet and an outlet; a pump support mounted in the tunnel and defining a portion of the water passage; an engine supported by the hull and having a drive shaft; a jet propulsion unit operatively connected to the drive shaft of the engine and supported in the tunnel within the water passage adjacent to the pump support, wherein the jet propulsion unit comprises a pump housing and an impeller; and a plurality of vanes extending into the water passage upstream of the impeller.
 2. The watercraft according to claim 1, wherein the jet propulsion unit further comprises a stator disposed adjacent to the impeller.
 3. The watercraft according to claim 1, wherein: the jet propulsion unit further comprises an inlet grate disposed proximate to the inlet to the water passage; and the plurality of vanes extend into the water passage downstream of the inlet grate.
 4. The watercraft according to claim 3, wherein the plurality of vanes are disposed at a closer proximity to the impeller than to the water passage inlet.
 5. The watercraft according to claim 1, wherein the pump support is disposed upstream of the pump housing and forms a water intake ramp.
 6. The watercraft according to claim 5, wherein the plurality of vanes are secured within the pump support.
 7. The watercraft according to claim 1, wherein the plurality of vanes extend inwardly from a passage in the pump support.
 8. The watercraft according to claim 1, wherein the plurality of vanes surround the drive shaft.
 9. The watercraft according to claim 8, wherein the plurality of vanes are disposed in the water passage such that a plane perpendicular to the drive shaft intersects each vane.
 10. The watercraft according to claim 1, wherein: the drive shaft includes a generally circular cross-section; and the vanes are concentrically disposed about the drive shaft.
 11. The watercraft according to claim 1, wherein the vanes are fixed with respect to the hull.
 12. The watercraft according to claim 1, wherein the plurality of vanes are disposed proximate to an inlet of the pump housing.
 13. The watercraft according to claim 1, wherein: the impeller comprises at least one rotating blade; and the plurality of vanes are disposed upstream of the at least one blade.
 14. The watercraft according to claim 1, wherein the plurality of vanes comprises at least six vanes.
 15. The watercraft according to claim 14, wherein the plurality of vanes comprises eight vanes.
 16. The watercraft according to claim 1, wherein each of the vanes have a substantially equal length.
 17. The watercraft according to claim 1, wherein each of the vanes is separated from the drive shaft by a substantially equal distance.
 18. The watercraft according to claim 1, wherein each of the vanes have a tapered leading edge and a trailing edge downstream of the tapered leading edge.
 19. The watercraft according to claim 18, wherein the leading edge is angled rearwardly with respect to the pump housing such that the leading edge is disposed at an acute angle relative to a plane perpendicular to a longitudinal axis of the drive shaft.
 20. The watercraft according to claim 19, wherein the trailing edge is substantially perpendicular to a longitudinal axis of the drive shaft.
 21. The watercraft according to claim 20, wherein the leading edge, the trailing edge and the longitudinal axis of the drive shaft are disposed in the same plane.
 22. The watercraft according to claim 19, wherein the vanes have a curvature such that the leading edge, the trailing edge and the longitudinal axis of the drive shaft are not disposed in the same plane.
 23. The watercraft according to claim 1, wherein the vanes are disposed around the inner periphery of an insert disposed within the water passage.
 24. The watercraft according to claim 23, wherein the insert is a ring and the plurality of vanes are evenly spaced around the inner periphery of the ring.
 25. The watercraft according to claim 23, wherein the insert includes an outer wall secured within the tunnel.
 26. The watercraft according to claim 23, wherein an inner periphery of the insert is generally annular.
 27. The watercraft according to claim 23, wherein the insert is secured within the pump support disposed within the water passage proximate to the pump housing.
 28. The watercraft according to claim 27, wherein the pump support is coupled to the pump housing.
 29. The watercraft according to claim 23, wherein the insert is secured within the pump housing.
 30. The watercraft according to claim 1, wherein the pump support comprises: a generally ring shaped body, the ring shaped body having an inner peripheral wall defining a passage extending therethrough, the plurality of vanes being disposed on the inner peripheral wall; and a pump housing attachment surface.
 31. The watercraft according to claim 1, wherein the plurality of vanes are disposed within the pump housing.
 32. The watercraft according to claim 1, wherein the jet propulsion unit further comprises a stator and a venturi disposed downstream of the stator.
 33. A jet propulsion unit pump support, comprising: a generally ring shaped body including an inner peripheral wall defining a passage extending therethrough, a plurality of vanes supported by the inner peripheral wall, and a pump housing attachment surface, the pump housing attachment surface being configured for attachment to a pump housing.
 34. The jet propulsion unit pump support of claim 33, further comprising a ring shaped insert secured within the inner peripheral wall, wherein the vanes extend from the insert.
 35. The jet propulsion unit pump support of claim 33, further comprising a ramp extending from the ring shaped body that forms a portion of a water inlet.
 36. The jet propulsion unit pump support of claim 35, wherein the plurality of vanes are disposed between the ramp and the pump housing attachment surface.
 37. A jet propulsion unit vane insert, comprising: a generally ring shaped body including an inner peripheral wall defining a passage extending therethrough, a plurality of vanes disposed on the inner peripheral wall, and an outer peripheral wall configured for attachment to a jet propulsion unit. 